微量钪、锆对Al-Zn-Mg合金铸态组织演变的影响
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摘要
对复合添加了稀土元素Sc、Zr的Al-Zn-Mg合金采用光学显微镜(OM)、电子探针(EPMA)、差热分析(DSC)等分析和测试方法,探究不同含量的Sc、Zr添加量对Al-Zn-Mg合金铸态组织演变的影响。结果表明,稀土元素Sc、Zr的复合添加对铸态晶粒产生了细化效果,铸态合金元素大多数偏聚在晶界或者晶内,随着Sc、Zr的含量增加,元素分布趋于均匀,第二相数目开始减少,晶粒大小也逐渐减少。470℃×24 h均匀化退火之后,枝晶组织得到消除,大部分非平衡T相也溶入基体,只有少量难溶的Fe、Si杂质相残留在晶界上,同时合金中重新析出小尺寸的MgZn_2相。随着Sc、Zr含量的增加,第二相的回溶和晶粒细化效果得到了提高。
The as-cast microstructure evolution of Al-Zn-Mg alloy with different content of Sc and Zr adding was investigated by means of optical microscopy (OM),electron probe micro-analyzer (EPMA) and differential scanning calorimetry (DSC) analysis. The results show that refinement effect on grain of the as-cast alloys is caused by the Sc and Zr addition and the element aggregation of the as-cast alloys occurred in grain boundary or inside the grain. With the increase of the contents of Sc and Zr,the distribution of elements becomes uniform,the number of secondary phase begins to decrease and the size of grain becomes smaller. After homogenization treatment at 470 ℃ for 24 h,dendritic microstructure is eliminated and most of nonequilibrium T phase is dissolved into matrix,there is only a little insoluble Fe and Si impurity phase remained on the grain boundary and undersized MgZn_2 re-precipitated from the alloys. With the increase of the contents of Sc and Zr,the dissolving of secondary phase and the refinement effect on grain can be improved.
The as-cast microstructure evolution of Al-Zn-Mg alloy with different content of Sc and Zr adding was investigated by means of optical microscopy (OM),electron probe micro-analyzer (EPMA) and differential scanning calorimetry (DSC) analysis. The results show that refinement effect on grain of the as-cast alloys is caused by the Sc and Zr addition and the element aggregation of the as-cast alloys occurred in grain boundary or inside the grain. With the increase of the contents of Sc and Zr,the distribution of elements becomes uniform,the number of secondary phase begins to decrease and the size of grain becomes smaller. After homogenization treatment at 470 ℃ for 24 h,dendritic microstructure is eliminated and most of nonequilibrium T phase is dissolved into matrix,there is only a little insoluble Fe and Si impurity phase remained on the grain boundary and undersized MgZn_2 re-precipitated from the alloys. With the increase of the contents of Sc and Zr,the dissolving of secondary phase and the refinement effect on grain can be improved.
引文
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[2]Zhang X,Liu S.Aerocraft aluminum alloys and their materials processing[J].Materials China,2013,32(1):39-55.
[3]Robson J D.Optimizing the homogenization of zirconium containing commercial aluminum alloys using a novel process model[J].Materials Science and Engineering A,2002,338(1/2):219-229.
[4]He Z B,Yin Z M,Lin S,et al.Preparation,microstructure and properties of Al-Zn-Mg-Sc alloy tubes[J].Journal of Rare Earths,2010,28(4):641-646.
[5]Ying D F,Yin Z M,Duan J Q,et al.Evolution of microstructure and properties in a new type 2 mm Al-Zn-Mg-Sc-Zr alloy sheet[J].Journal of Alloys and Compounds,2012,517(2):118-126.
[6]Richard A,Karnesky,Marsha E,et al.Effects of substituting rare-earth elements for scandium in a precipitation-strengthened Al-0.08at.%Sc alloy[J].Scripta Materialia,2006,55(5):437-440.
[7]潘利文,罗涛,林覃贵,等.稀土铝合金最新研究进展[J].轻合金加工技术,2016,44(9):12-16.Pan Liwen,Luo Tao,Lin Qingui,et al.Latest research progress of rare earth aluminum alloy[J].Light Alloy Fabrication Technology,2016,44(9):12-16.
[8]柏振海,熊俊,罗兵辉,等.钪在铝合金中的作用[J].铝加工,2001,24(6):33-37.Bo Zhenghai,Xiong Jun,Luo Binhui,et al.The effect of Sc on aluminum alloy[J].Aluminum Fabrication,2001,24(6):33-37.
[9]贺永东,张新明,游江海.复合添加微量Sc,Zr对Al-Zn-Mg-Cu合金组织性能的影响[J].稀有金属材料与工程,2007(4):665-670.He Yongdong,Zhang Xinming,You Jianghai.Effects of minor contents of Sc and Zr on microstructure and mechanical properties of Al-Zn-MgCu alloy[J].Rare Metal Materials and Engineering,2007(4):665-670.
[10]何运斌,潘青林,刘元斐,等.Sc和Zr复合微合金化对Al-Zn-Mg-Cu合金组织与性能的影响[J].轻合金加工技术,2005(9):46-48.He Yunbin,Pan Qinglin,Liu Yuanfei,et al.Effects of Minor Scandium and Zirconium on Microstructure and Tensile Properties of Al-Zn-Mg-Cu Alloys[J].Light Alloy Fabrication Technology,2005(9):46-48.
[11]樊喜刚.Al-Zn-Mg-Cu-Zr合金组织性能和断裂行为的研究[D].哈尔滨:哈尔滨工业大学,2007.
[12]Christian B Fuller,Albert R Krause,David C Dunand,et al.Microstructure and mechanical properties of a 5754 aluminum alloy modified by Sc and Zr additions[J].Materials Science and Engineering A,2002,338(1):8-16.